Opening and Working Enquiries: Working an enquiry - revised statement made before the first or second specified dates but after enquiry notice issued
If the customer(s) has reported their actual income either before the first or second specified dates, see CCM11040 and CCM11050, you may have issued an enquiry notice before whichever of those dates applies. If the customer(s) subsequently realises they have made a mistake in their statement they can send in a revised one, as long as they do so before the first or second specified dates, as appropriate. The fact you have already opened an enquiry into their entitlement for the year does not affect their right to send in a revised statement. Nor does the fact they have sent in a revised statement affect the validity of your enquiry notice - it was properly issued after the final decision was made.
Where a revised statement is received for a case which is under enquiry, it will be referred to you without being processed. You should incorporate it into your existing enquiry. You are not obliged to make a revised decision on the revised statement (S18(9) says that you may do so - which means you don’t have to). So when you settle your enquiry, you will simply need to make a single enquiry decision (S19(3)) which also takes account of the revised statement.